Mysql查询获取每个类别的前5个子类别

Question

我需要一个查询;条件是：

我想从每个类别中只选择最新的5个子类别;

当前的查询是：

SELECT a.id,a.catagory_name,b.id as sucid,b.subcatagory_name 
FROM category a 
LEFT JOIN subcategory b ON a.id = b.catagory_id 
WHERE a.active='y' AND b.active='y' 
ORDER BY a.priority,b.subcatagory_name 

Answer 1

请试试这个。

SELECT a.id,a.catagory_name,b.id as sucid,b.subcatagory_name 
FROM category a 
LEFT JOIN subcategory b ON a.id = b.catagory_id 
WHERE a.active='y' AND b.active='y' 
ORDER BY a.priority,b.category_id DESC 
LIMIT 0,5 

这可能适合你。

Answer 2

让我们试试这个：

SELECT a.id,a.catagory_name,B.id as sucid,B.subcatagory_name 
FROM category a 
(SELECT id,subcatagory_name FROM subcategory WHERE catagory_id = a.id ORDER BY id DESC LIMIT 5) AS B 
ON a.id = B.catagory_id 
ORDER BY a.priority,B.category_id;